Effect of diffusion of Ni and B on the microstructure and hardness of Ti Cp

The present work has the aim to study the effect of the diffusion of Ni and Ni-B on the microstructure and the hardness of Ti Cp. Ni and NiB were deposited on the titanium by electrolytic and electroless deposition, respectively. The treatments of diffusion were carried out at temperatures below and above the titanium β-transus temperature in order to examine the effect of the two different phases on diffusion behaviour and the final microstructure. The samples, after holding at the temperature of diffusion for 1 h, were cooled in furnace at 5 °C/min. The resulting microstructure was investigated by optical microscope (OM), SEM-EDS, glow discharge optical spectrometer (GDOS), XRD and micro-hardness test. Better results were obtained at temperature above the β-transus, which can be attributed to the increase of diffusion due, both, to the high temperature and the cubic body-centred structure that Ti assumes above the β-transus.